The present invention relates to a radio receiver and, more particularly, to a radio receiver selectively operable in a station search mode or a station select mode.
In a conventional voltage synthesizer type radio receiver operable in a station search mode (automatic scanning mode) or a station select mode (presetting mode), a ramp voltage from a ramp generator is supplied to a voltage-controlled local oscillator through a hold circuit in the station search mode, thereby to change a local frequency. Through a continuous change of the oscillating frequency of voltage-controlled local oscillator, a receiving frequency band is automatically scanned and, when the receiver is tuned to a broadcast signal, a tuning detecting means causes the hold circuit to hold a magnitude of the ramp voltage at the tuning time. In the station select mode, the frequency information for a broadcast station stored in a memory is converted into a corresponding DC voltage by a digital-to-analog converter which in turn is applied to the local oscillator. In this way, the receiver is tuned to the selected broadcast station.
In the above-mentioned voltage synthesizer type receiver, when the oscillating frequency of the local oscillator changes in accordance with temperature, etc., the receiver is caused to be detuned.